View Poll Results: Engine vs Rotor Braking
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Engine vs Rotor Braking
09-17-2002, 05:53 PM
#52
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Brakes are for stopping the car and shifting is for keeping the engine at the correct RPM , That's it .
For spirited driving keep engine RPM higher , press brake petal harder .
Using the engine for a brake would be like a "Jake Brake " on a diesel truck . They connect throttle ( so you can't add fuel to engine while using the Jake Brake) to the Jake Brake petal and there is a damper in the exhaust to slow the flow of exhaust gas .
Our cars have very little ability to brake under engine braking . Using the art of down shifting and braking at the same time , as was posted before allows engine to stay in the RPM range that is required for the type of driving that you are doing .
Adding engine braking to normal petal braking does not increase the ability of the car to stop . Once you push the petal hard enough to invoke ABS , there is nothing extra that you can do , other that purchase stickier tires ,with a larger foot print , before you pushed the petal.
I also agree that the stresses put on the transmission and moving pats of the engine are also a good reason not to engine brake . The pistons and rods are designed for an explosion in the combustion chamber for high load application , not engine braking .
brad
For spirited driving keep engine RPM higher , press brake petal harder .
Using the engine for a brake would be like a "Jake Brake " on a diesel truck . They connect throttle ( so you can't add fuel to engine while using the Jake Brake) to the Jake Brake petal and there is a damper in the exhaust to slow the flow of exhaust gas .
Our cars have very little ability to brake under engine braking . Using the art of down shifting and braking at the same time , as was posted before allows engine to stay in the RPM range that is required for the type of driving that you are doing .
Adding engine braking to normal petal braking does not increase the ability of the car to stop . Once you push the petal hard enough to invoke ABS , there is nothing extra that you can do , other that purchase stickier tires ,with a larger foot print , before you pushed the petal.
I also agree that the stresses put on the transmission and moving pats of the engine are also a good reason not to engine brake . The pistons and rods are designed for an explosion in the combustion chamber for high load application , not engine braking .
brad
09-17-2002, 06:40 PM
#54
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Originally posted by dwb1
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For spirited driving keep engine RPM higher , press brake petal harder .
...
The pistons and rods are designed for an explosion in the combustion chamber for high load application , not engine braking .
brad
...
For spirited driving keep engine RPM higher , press brake petal harder .
...
The pistons and rods are designed for an explosion in the combustion chamber for high load application , not engine braking .
brad
A petal is what grows on a flower to make it so pretty.
Peddle is what salesmen do.
Two S2000s: one is on a perpetual uphill, fuel and air coming in, "explosion in the combustion chamber", car moving up hill. The other S2000 is on a perpetual downhill, engine braking at equivalent RPM. Which pistons and rods last longer?
09-19-2002, 01:15 PM
#58
Originally posted by S2K2GO!!!
You are SO very wrong, my friend. Max possible cylinder pressures attainable engine braking are <200 PSI, max possible BMEP during power stroke is many hundreds of PSI. A similar ratio of potential stresses runs through the entire drive train when engine braking vs accel. Engine braking with good technique is harmless if rev limits are not exceeded. Excessive use of brakes leads to brake fade with associated compromise of control, warped rotors, $$$. True, the car can't be slowed as rapidly with the engine as it can be accelerated, but the best technique is to use engine braking whenever you can(for me that's about 90% of my deceleration needs in typical driving), and brakes as-needed beyond that.
You are SO very wrong, my friend. Max possible cylinder pressures attainable engine braking are <200 PSI, max possible BMEP during power stroke is many hundreds of PSI. A similar ratio of potential stresses runs through the entire drive train when engine braking vs accel. Engine braking with good technique is harmless if rev limits are not exceeded. Excessive use of brakes leads to brake fade with associated compromise of control, warped rotors, $$$. True, the car can't be slowed as rapidly with the engine as it can be accelerated, but the best technique is to use engine braking whenever you can(for me that's about 90% of my deceleration needs in typical driving), and brakes as-needed beyond that.
LOL
09-19-2002, 03:07 PM
#59
Registered User
Originally posted by S2K2GO!!!
You are SO very wrong, my friend. Max possible cylinder pressures attainable engine braking are <200 PSI, max possible BMEP during power stroke is many hundreds of PSI. A similar ratio of potential stresses runs through the entire drive train when engine braking vs accel. Engine braking with good technique is harmless if rev limits are not exceeded. Excessive use of brakes leads to brake fade with associated compromise of control, warped rotors, $$$. True, the car can't be slowed as rapidly with the engine as it can be accelerated, but the best technique is to use engine braking whenever you can(for me that's about 90% of my deceleration needs in typical driving), and brakes as-needed beyond that.
You are SO very wrong, my friend. Max possible cylinder pressures attainable engine braking are <200 PSI, max possible BMEP during power stroke is many hundreds of PSI. A similar ratio of potential stresses runs through the entire drive train when engine braking vs accel. Engine braking with good technique is harmless if rev limits are not exceeded. Excessive use of brakes leads to brake fade with associated compromise of control, warped rotors, $$$. True, the car can't be slowed as rapidly with the engine as it can be accelerated, but the best technique is to use engine braking whenever you can(for me that's about 90% of my deceleration needs in typical driving), and brakes as-needed beyond that.
